The present invention relates to a method and device for making a series of cuts at different angles in one or more panels using a panel sawing machine.
As is known, panel sawing machines are used to cut large panels, slabs or sheets (or stacks of these), made mainly of wood base materials but also of plastic or composite materials, in order to make smaller panels.
Machines of this kind usually comprise a worktable on which one or more panels, placed over one another to form a substantially rectangular stack, are positioned, and a handling device that feeds the panel stack to one or more cutting stations positioned at different angles. In some cases, however, the panels have to be cut several times and only if they are rotated about the cutting line, cut a first time a then rotated and cut again.
In known methods and machines that normally carry out these operations, a portion of the panel worktable, normally the central portion of the worktable, is made to rotate. Alternatively, the entire stack is turned by mechanical arms which are mounted along the sides of the worktable. These mechanical arms grip the panel stack by one edge and turn it by sliding it on the surface of the worktable which may be made of low friction material or which, more usually, consists of a set of supporting elements which enable the panel to be moved along the two Cartesian axes defining the main plane in which the panel stack lies.
These methods have considerable disadvantages due mainly to the slowness and cost of the machinery required.
In a more advanced solution disclosed by the Applicant (see U.S. Pat. No. 5,257,900), a portion of the panel stack close to the corner opposite the cutting line is held by a gripper mounted on the panel stack handling device. At the same time, a push roller acts against the side of the stack adjacent to the cutting line (see FIG. 2 of the drawings accompanying this U.S. patent). The panels are then rotated a first time through 90 degrees by moving the gripper towards the cutting line in a direction perpendicular to the cutting line while the push roller is driven towards the gripper""s path in a direction parallel to the cutting line. Next, the gripper is disengaged from the panel stack and the handling device-crossbeam is moved in the opposite direction back to the end of the stack opposite the cutting line. The same device is then used to push the panels towards the cutting line so that the first series of cuts can be made.
Once this step has been completed, the gripper once again engages a portion of the panel stack close to the corner opposite the cutting line while the push roller acts against the side of the stack adjacent to the direction of movement of the gripper (see FIG. 3 of the drawings accompanying this U.S. patent). The second rotation of the panels is carried out in the same direction as the first by moving the gripper towards the cutting line in a direction perpendicular to the latter and moving the push roller away from the gripper""s path in a direction parallel to the cutting line. As in the step described above, the gripper is disengaged from the panel stack and the handling device is moved in the opposite direction back to the end of the panel stack opposite the cutting line. The device is then used to push the panel stack towards the cutting line so that the second series of cuts can be made.
This method and the apparatus that implements it have considerable disadvantages.
First of all, the second rotation, unlike the first, moves the center of gravity of the panels away from the cutting line. The handling device must therefore push the stack along an additional path before it can be cut. Owing to the large size of the panels, this means lengthening the process considerably.
Another disadvantage is linked to the machine architecture, that is to say, the use of a gripper mounted on the panel handling device. After each of the two rotations, the device must return to the starting position before the panel stack can be pushed towards the cutting line. This further slows down the cutting process.
The aim of the present invention is to overcome the drawbacks of the prior art described above.
The invention has for a specific object to provide a method and device capable of optimizing the time required to make a series of cuts at different angles in one or more panels using a panel saw.
The above aim and object are achieved by a method and a device, as described in the claims, for making a series of cuts at different angles in one or more panels using a panel saw.